Lesser Nighthawks (Chordeiles acutipennis) sit on the ground of the chaparral hilltops and trill this toad-like trill on the summer nights around central Arizona. This one was at Peck's Lake [Arizona] May 20th, 1999. The sound is very hard to localize, since it is so low, quiet and "generic" (high-pitched sounds are much easier to find), and they are generally closer to you than they seem to be.
Douglas Von Gausig (recordist; copyright holder), Naturesongs.com
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